Datastore Clients¶

The main component for pulsar datastore clients is the Store class which encapsulates the essential API for communicating and executing asynchronous commands on remote servers.

Getting Started¶

To create a data Store client one uses the create_store() function with a valid connection string:

>>> from pulsar.apps.data import create_store
>>> store = create_store('redis://user:password@127.0.0.1:6500/11')
>>> store.name
'redis'
>>> store.database
'11'
>>> store.dns
'redis://user:password@127.0.0.1:6500/11'

Additional parameters can be passed via the connection string or as key-valued parameters. For example:

>>> store = create_store('redis://user:password@127.0.0.1:6500/11',
                         namespace='test_')
>>> store.dns
'redis://user:password@127.0.0.1:6500/11?namespace=test_'

Connection String¶

The connection string is a way to specify the various parameters for the data store connection. All Store support a connection string of the form:

<scheme>://<username>:<password>@<host>/<database>?param1=...&param2=...

where:

schema is the store name
database is the database name (or number for redis)
username is an optional database username
password is an optional database password

Implement a Store¶

When implementing a new Store there are several methods which need to be covered:

ping() to check if the server is available
connect() to create a new connection
execute() to execute a command on the store server

All registered data stores are stored in the data_stores dictionary:

from pulsar.apps.data import data_stores

Pulsar provides two implementations, the redis client and the pulsards client.

API¶

The main component of the data store API is the create_store() function which creates in one function call a new Store object which can be used to interact with the backend database.

Create store¶

pulsar.apps.data.store.create_store(url, **kw)[source]¶

Create a new Store for a valid url.

Parameters:

url –

a valid url takes the following forms:

Pulsar datastore:

pulsar://user:password@127.0.0.1:6410

Redis:

redis://user:password@127.0.0.1:6500/11?namespace=testdb

kw – additional key-valued parameters to pass to the Store initialisation method. It can contains parameters such as database, user and password to override the url values. Additional parameters are processed by the Store._init() method.

Returns:

a Store.

Start store¶

pulsar.apps.data.pulsards.startds.start_store(app, url, workers=0, **kw)[source]¶: Equivalent to create_store() for most cases excepts when the url is for a pulsar store not yet started. In this case, a PulsarDS is started.

Register a new store¶

pulsar.apps.data.store.register_store(name, dotted_path)[source]¶: Register a new Store with schema name which can be found at the python dotted_path.

Store¶

class pulsar.apps.data.store.Store(name, host, database=None, user=None, password=None, encoding=None, **kw)[source]¶

Base class for an asynchronous data stores.

A Store should not be created directly, the high level create_store() function should be used instead.

_host¶: The remote host, tuple or string

_user¶: The user name

_password¶: The user password

name¶: Store name

database¶: Database name/number associated with this store.

encoding¶: Store encoding (usually utf-8)

dns¶: Domain name server

urlparams¶: url parameters in dns query

database_create(dbname=None, **kw)[source]¶

Create a new database in this store.

By default it does nothing, stores must implement this method only if they support database creation.

Parameters:	dbname – optional database name. If not supplied a database with `database` is created.

table_all(**kw)[source]¶: Information about the table/collection mapping model

RemoteStore¶

class pulsar.apps.data.store.RemoteStore(name, host, loop=None, protocol_factory=None, **kw)[source]¶

Base class for remote data stores.

It is an Producer for accessing and retrieving data from remote data servers such as redis.

connect()[source]¶: Connect with store server

execute(*args, **options)[source]¶: Execute a command

ping()[source]¶: Used to check if the data server is available

client()[source]¶: Get a client for this store if implemented

pubsub(**kw)[source]¶: Obtain a PubSub handler for this store if implemented

channels(**kw)[source]¶: Obtain a Channels handler for this store if implemented

close()[source]¶: Close all open connections

flush()[source]¶: Flush the store.

encode_bytes(data)[source]¶

Encode bytes data

Parameters:	data – a bytes string
Returns:	bytes or string

dencode_bytes(data)[source]¶

Decode bytes data

Parameters:	data – bytes or string
Returns:	bytes